Vermeulen A, Devaux C, Herman M
Appl Opt. 2000 Nov 20;39(33):6207-20. doi: 10.1364/ao.39.006207.
A method has been developed for retrieving the scattering and microphysical properties of atmospheric aerosol from measurements of solar transmission, aureole, and angular distribution of the scattered and polarized sky light in the solar principal plane. Numerical simulations of measurements have been used to investigate the feasibility of the method and to test the algorithm's performance. It is shown that the absorption and scattering properties of an aerosol, i.e., the single-scattering albedo, the phase function, and the polarization for single scattering of incident unpolarized light, can be obtained by use of radiative transfer calculations to correct the values of scattered radiance and polarized radiance for multiple scattering, Rayleigh scattering, and the influence of ground. The method requires only measurement of the aerosol's optical thickness and an estimate of the ground's reflectance and does not need any specific assumption about properties of the aerosol. The accuracy of the retrieved phase function and polarization of the aerosols is examined at near-infrared wavelengths (e.g., 0.870 mum). The aerosol's microphysical properties (size distribution and complex refractive index) are derived in a second step. The real part of the refractive index is a strong function of the polarization, whereas the imaginary part is strongly dependent on the sky's radiance and the retrieved single-scattering albedo. It is demonstrated that inclusion of polarization data yields the real part of the refractive index.
已开发出一种方法，可从太阳透射、光晕以及太阳主平面内散射和偏振天光的角分布测量中反演大气气溶胶的散射和微物理特性。利用测量的数值模拟来研究该方法的可行性并测试算法性能。结果表明，通过辐射传输计算校正多次散射、瑞利散射和地面影响的散射辐射亮度和偏振辐射亮度值，可获得气溶胶的吸收和散射特性，即单次散射反照率、相位函数以及入射非偏振光单次散射的偏振度。该方法仅需测量气溶胶的光学厚度并估计地面反射率，无需对气溶胶特性做任何特定假设。在近红外波长（如0.870μm）下检验了反演的气溶胶相位函数和偏振度的准确性。第二步推导气溶胶的微物理特性（粒径分布和复折射率）。折射率的实部是偏振的强函数，而虚部强烈依赖于天空辐射亮度和反演的单次散射反照率。结果表明，包含偏振数据可得出折射率的实部。
